known in the history of
Islam as the Chief of
Hypocrites.
al-Munafiqun
63:8 is said to be an insult by him on
Muhammad. It was recorded that
the Muslims were very angry and even his own son (who had became a Muslim)
wanted to kill him. Muhammad, however, did not grant that request nor allow
anyone from among his Companions to punish Abdullah bin Ubayy in any manner
whatsoever. (ref Ibn Ishaq: Al-Seera tun Nabawiyya by Ibn Hashim,
pt. III; p. 155).

Later, when Abdullah died, it was reported that Muhammad wanted to
conduct his funeral.
Umar
reminded Muhammad that
Allah has forbidden him
to offer funeral prayer for the hypocrites. Muhammad replied that it does
not avail whether he ask or not, since even if he were to ask for forgiveness
seventy times, Allah will not forgive them. In other words, Muhammad believed
that his prayers have no consequences and therefore he is allowed to do
it.
After the funeral prayer,
at-Taubah 9:84
was said to be revealed forbidding prayer for hypocrites, rebuking
Muhammad. Muhammad is said to put his saliva over the dead body and clothed
it in his shirt. (ref:
Sahih Bukhari 2.359,
Sahih Bukhari 2.360).